GUANTANAMO BAY NAVAL BASE, Cuba — The Haiti earthquake is giving the American base at Guantanamo Bay a new mission: supplying aid to the devastated island nation and potentially detaining thousands of Haitian migrants captured at sea.

President Barack Obama's deadline for closing the base prison expires Friday with no new date in sight, but a huge effort to provide earthquake aid is just getting started.

The U.S. has designated Guantanamo, less than 200 miles from Haiti, as the hub of the aid operation. Dozens of helicopters and planes take off daily to ferry supplies and personnel to the stricken country or to American ships off the coast.

In ordinary times, the base airstrip is ghostly, with only about three flights a day, including the sporadic release of prisoners.

Activity related to the aid effort is expected to intensify in coming weeks, and no one knows when those efforts might end. At the same time, U.S. officials refuse to predict when the detention center, which now holds 198 men, will get a new date for closure.

Outpost transformed
Obama directed the government shortly after his inauguration to close the detention center within a year. But those efforts bogged down. Congress attempted to block the transfer of detainees to U.S. prisons, and other countries are still reluctant to accept them.

Authorities are also still deciding which detainees will be prosecuted and which might stay in custody without charges for security reasons.

While the detention center staff try to carry on as normal, the rest of Guantanamo has been transformed. The sleepy outpost at the cactus-studded southeast corner of Cuba has so many people coming in to help the Haiti aid effort that officials are struggling to find places for them to sleep. Service members have been told to cancel plans to host visitors at the base. New requests for leave have been banned.

The military plans to clear part of a dormant airfield so heavy-lift helicopters can pick up large pallets of supplies and fly them directly to Haiti. Plans are also under consideration to set up a 150-bed mobile hospital to treat casualties. Already, the base hospital has been used to treat Americans wounded in the earthquake.

In addition, officials have sought permission from Cuba to allow American aircraft carrying disaster-relief supplies to overfly Cuban territory rather than flying around it.

Blaisdell said the two governments will be discussing details of the proposal at their regular monthly meeting at the edge of the base.

Workers have also been preparing tents at Guantanamo Bay for Haitian migrants in case the earthquake spurs a mass migration. This is not a new role for the base: At any given moment, the facility temporarily holds small groups of migrants, mostly from Cuba.

In the 1990s, Guantanamo housed tens of thousands of Haitian boat people until they could be sent home.

About 100 tents, each capable of holding 10 people, have been erected. The U.S. has capacity to hold up to 13,000 at that site, which is on the opposite side of the base, separated by 2 1/2 miles of water, from the detention center for terrorism suspects. Blaisdell said he is considering additional places in case more space is needed.

A more gratifying missionAt the prison, Friday's deadline for the closure of the base prison was a nonevent.

Behind walls of razor wire, officials say they will be on alert for protests by prisoners. But Army Col. Bruce Vargo, the guard force commander, said the reduced population and the decision to house nearly 75 percent of the men in communal settings has eased tensions. He does not expect significant trouble.

The delay in closing the base has angered Guantanamo's many critics, but attorneys for prisoners say most of their clients were always skeptical that they would be going home soon. Many of them now have regular access to the news and could read copies of Obama's order posted around the camps.

"When they saw how slow the review process became and the tiny trickle of men transferred from Guantanamo, they were realistic and saw it would be impossible to meet the Jan. 22 deadline," said David Remes, a Washington attorney for 18 prisoners.

Navy Rear Adm. Thomas Copeman, commander of the task force that runs the detention center, views with pride the base's role in trying to solve the humanitarian crisis.

"The ability to conduct real-world humanitarian assistance and disaster relief ... that's more exhilarating at the moment then walking the block in the detention camp, not to say that walking the block is not an extremely important mission for the United States but probably not as gratifying as saving someone's life."

Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.